If the most recent rumors are true the 6.1" LCD version will get less enhanced features, single lens camera, no Force Touch, less RAM, but that part I don't think will be as critcal since the X has 3GB RAM. They seem intent on pushing FaceID forward based on what we have heard so far and that would indicated 6S, 7 and 8 series would be the last touchiD versions and will fade out slowly over time. There will always be those who dont' want faceID.
The 5.8" X is a good size and depending on how the rumored 6.5" X Plus is I may opt for it. This time around though I won't buy on launch unless they offer a SIM Free version on launch day otherwise I will just ride it out a few months.